The Mendocino Complex Fire was a large complex of wildfires that burned in northern California for more than three months in 2018. It consisted of two wildfires, the River Fire and Ranch Fire, which burned in Mendocino, Lake, Colusa, and Glenn Counties in the U.S. State of California, with the Ranch Fire being California's single-largest recorded wildfire at the time until the Dixie Fire in 2021. The Ranch Fire burned eight miles northeast of Ukiah, and the River Fire burned six miles north of Hopland, to the south of the larger Ranch Fire. First reported on July 27, 2018, both fires burned a combined total of 459,123 acres (1,858 km2), before they were collectively 100% contained on September 18, though hotspots persisted until the complex was fully brought under control on January 4, 2019. The Ranch Fire alone burned 410,203 acres (1,660 km2), making it the largest wildfire in modern California history at the time until the August Complex fire that occurred in 2020. The Ranch Fire also surpassed the size of the 315,577-acre Rush Fire, which burned across California and Nevada, as well as the Santiago Canyon Fire of 1889, which was previously believed to have been California's all-time largest wildfire.

The Holy Fire was a wildfire that burned in the Cleveland National Forest in Orange and Riverside Counties, California. The wildfire started on August 6, 2018 at around 1:15 PM PDT, in the vicinity of Trabuco Canyon. A suspected arsonist was booked into the Orange County jail in Santa Ana, California but found not guilty in 2023. The blaze burned 23,136 acres (94 km2) and destroyed 18 buildings, before it was fully contained on September 13, 2018. While the fire was actively spreading in early and mid-August, residents of the nearby cities of Corona, Temescal Valley, and Lake Elsinore were placed under evacuation orders.